1. Field of the Disclosure
The disclosure generally relates to a liquid crystal display (LCD) panel, and more particularly, to a LCD panel offering an anti-peep effect.
2. Description of Related Art
A display usually offers a wide viewing angle display effect in order to allow multiple viewers to view the displayed images. However, in some cases (for example, when confidential information is read or a password is input), the wide viewing angle display effect may cause confidential information to be peeped by others and accordingly leak of the confidential information. Thus, in order to satisfy both requirements mentioned above, displays switchable between a wide viewing angle display mode and a narrow viewing angle display mode have become one of the mainstream products in the display market.
Following anti-peep mechanisms are usually adopted by conventional displays.
The first conventional anti-peep mechanism is to directly attach an anti-peep film to the exterior surface of a display panel.
An anti-peep film provides a privacy protection effect by inhibiting the brightness at large viewing angles so that a viewer from the side cannot read the displayed information clearly. This technique is very straightforward and requires easily accessed material. However, because an additional optical film is used, the front view optical characteristic and display quality of the display panel are affected. Besides, this technique brings inconvenience to the user as the anti-peep film has to be manually attached and removed.
The second conventional anti-peep mechanism is to control the backlight source.
In this technique, a backlight source which can emit highly collimated light and a voltage-controlled diffuser (for example, a polymer dispersed liquid crystal (PDLC) film) are adopted. When the voltage is turned off, the voltage-controlled diffuser diffuses the collimated light to emit light to the side, so that a wide viewing angle display mode is achieved. On the other hand, when the voltage is turned on, the voltage-controlled diffuser does not diffuse the collimated light, so that a narrow viewing angle display mode is achieved. This technique is to adjust the brightness at large viewing angles, so as to prevent the displayed information from being read from the side, by controlling the backlight emission angle. Theoretically, this technique offers a good anti-peep effect and allows the user to switch between the two display modes conveniently. However, in an actual application, it is impossible to obtain a completely collimated light due to the difficulty in optical path control. Even though this technique can reduce the distribution of backlight at large viewing angles, it cannot reduce the brightness at the large viewing angles to an unrecognizable extent. Thus, this technique does not provide a satisfying anti-peep effect.
The third conventional anti-peep mechanism is to adopt a viewing angle control module.
In this technique, a viewing angle control module (panel) is further disposed in a normal display module (display panel). A wide viewing angle display mode and a narrow viewing angle display mode are switched by controlling the on and off of the viewing angle control module with a voltage supply. In the wide viewing angle display mode, the image display is not affected and accordingly the original image display quality can be retained. While in the narrow viewing angle display mode, the brightness at large viewing angles is effectively inhibited so that the displayed information cannot be read from the side. However, because an additional module is adopted, the weight and thickness of the entire display are doubled, and the hardware cost thereof is also increased.
As described above, some of the original characteristics (for example, display quality, optical characteristics, thickness, and weight, etc) of a display will be sacrificed by adopting any one of aforementioned conventional anti-peep mechanisms. Thereby, an improved anti-peep technique is desired.